Photographic compositions and processes for making same

ABSTRACT

Photographic silver-halide emulsions comprising silver-halide grains which have been formed in the presence of a water-soluble nitrite. In one aspect, photographic silver-halide emulsions comprising said grains provide improved direct-print emulsions. In another aspect, this invention relates to a process for improving the photographic properties of a direct-print composition by adding water-soluble nitrites to the precipitation medium wherein the silver-halide grains are formed.

United States Patent [72] Inventor Richard W. Karlson Rochester, N.Y.

[21] Appl. No. 766,322

[22] Filed Oct. 9, 1968 [45] Patented Oct. 26, 1971 [73] AssigneeEastman Kodak Company Rochester, N.Y.

[54] PHOTOGRAPHIC COMPOSITIONS AND PROCESSES FOR MAKING SAME 12 Claims,No Drawings [52] US. Cl 96/94 R, 96/108, 96/119 [51] Int. Cl G03c 1/06[50] Field of Search 96/108, 110, 94 R,94 BF; 1/119 [56] ReferencesCited UNITED STATES PATENTS 2,112,140 3/1938 Brooker et al. 260/240.6

2,493,747 1/ 1950 Brooker et a1. 260/2404 2,493,748 1/1950 Brooker etal. 260/2404 2,519,001 8/ 1950 Sprague 260/2401 Primary Examiner-WilliamD. Martin Assistant Examiner- Bernard D. Pianalto Attorneys-W, H. J.Kline, Bernard D. Wiesde and Gerald E.

Battist ABSTRACT: Photographic silver-halide emulsions comprisingsilver-halide grains which have been formed in the presence of awater-soluble nitrite. In one aspect, photographic silver-halideemulsions comprising said grains provide improved direct-printemulsions. In another aspect, this invention relates to a process forimproving the photographic properties of a direct-print composition byadding water-soluble nitrites to the precipitation medium wherein thesilver-halide grains are formed.

PHOTOGRAPIIIC COMPOSITIONS AND PROCESSES FOR MAKING SAME This inventionrelates to new photographic silver-halide emulsions. In one aspect, thisinvention relates to direct-print silver-halide emulsions wherein thesilver-halide grains are formed in the presence of a water-solublenitrite. In another aspect, this invention relates to a novel method ofimproving the photographic properties, such as print stability, speed,Dmin, discrimination, etc., in direct-print silver-halide emulsions.

It is known in the art to add various addenda to direct-printsilver-halide compositions to improve the photographic properties ofthese compositions. Compounds such as thioureas, sodium nitrite,stannous chloride, urazoles and the like have been added as coatingaddenda to provide halogen acceptors in direct-print compositions. It isalso known to use com-- pounds such as thiocyanates, thioethers and leadsalts during the formation of the silver-halide grains to provideimproved image properties in direct-print compositions. However, it isdesirable to provide means which will further improve the photographicproperties of direct-print compositions.

We have now found that direct-print compositions having improvedphotographic properties can be obtained with a direct-printsilver-halide emulsion therein the grains of said silver-halide emulsionare formed in the presence of a watersoluble nitrite. In a preferredembodiment of this invention, the direct-print composition comprises ahalogen acceptor as an addendum. In another preferred embodiment, thehalide of said silver-halide is predominantly bromide.

According to the present invention, water-soluble nitrites I can beeffectively utilized during the formation of the silverhalide grains toprovide improved photographic properties such as improved printstability, photographic speed, Dmin, discrimination, etc. Generally, thewater-soluble nitrites can be added to any of the solutions used in theprecipitation step of forming the silver-halide grains. Typical usefulwater-soluble nitrites include sodium nitrite, potassium nitrite, andthe like. The water-soluble nitrites are generally added to thesolutions to provide a concentration of 1X10 to about one mole andpreferably from 0.001 to about 0.5 mole of water-soluble nitrite permole of silver halide formed in the precipitation step. in a preferredembodiment, the water-soluble nitrites are those which are soluble inwater at room temperature in a concentration of at least 0.1 gram per100 ml. of water. Those nitrites which are highly preferred in theemulsions are the alkali metal nitrites which have a water solubility ofat least 10 grams per 100 ml. of water at room temperature.

It is not completely understood whether the nitrite is incorporated intothe grain or whether reaction products of the nitrite are responsiblefor the improved photographic properties. Therefore, it is contemplatedto be within the scope of the invention that the grains are formed inthe presence of nitrites (or reaction products thereof) as long as theyare added to or present in the precipitation medium during formation ofthe silver-halide grains.

The water-soluble nitrites can be generally utilized in any of thephotographic compositions which will function as directprint emulsions.Suitable silver halides include internally sensitive silver bromide,silver iodobromide, silver chlorobromide, silver chloroiodobromide, andthe like. The preferred emulsions are those wherein the halide of thesilver is predominantly bromide. in a typical embodiment, the preferredemulsions are direct-print emulsions having higher internal sensitivitythan surface sensitivity as' described by Hunt in Photographic Scienceand Engineering," Vol. 5, No. 2, Mar.-Apr., 1961, pages 104-108. For adescription of suitable emulsions, reference is made to Davey et al.,U.S. Pat. No. 2,592,250 issued Apr. 8, 1952; U.S. Pat. No. 3,206,316;Porter et al., U.S. Pat. No. 3,206,313; Sutherns, U.S. Ser. No. 667,091filed Sept. 12, 1967; Kitze, Belgian Pat. No. 689,515 issued Jan. 13,1967; Glafkides, Photographic Chemistry," Vol. 1, pages 31-32, FountainPress, London; and in McBride, U.S. Pat. No. 3,271,157 issued Sept. 6,1966, and U.S. Pat. No. 3,287,137.

In one preferred embodiment, the silver-halide compositions aredirect-print compositions which contain halogen acceptors. Generally,suitable halogen acceptors are compounds which enhance the photolyticyield (as determined by radiographic analysis, for example) and/or thephotolytic density of a printout emulsion. Typical halogen acceptors foruse in the present emulsions include those disclosed in McBride, U.S.Pat. No. 3,287,137; McBride, U.S. Pat. No. 3,271,157; and Kitze, U.S.Pat. No. 3,241,971. In one preferred embodiment, nitrogen-containinghalogen acceptors according to the Mc- Bride patents, above, areutilized in the emulsions. In another preferred embodiment, the halogenacceptors are of the type disclosed in Kitze, U.S. Pat. No. 3,241,971,which contain mercaptan groups and especially the heterocyclicmercaptans and thiones. In yet another embodiment, the halogen acceptorsare urazoles of the type disclosed in in Bacon et al., U.S. Pat. No.3,396,017 issued Aug. 6, 1968-.

The emulsions of the invention are generally made with a slight excessof halide ion present over that necessary initially to precipitate allof the silver as silver halide in the preparation thereof.

The silver-halide emulsions of this invention can be sensitized withvarious dyes. Typical dyes are disclosed in Mc- Bride, U.S. Pat. No.3,287,136; Brooker, U.S. Pat. Nos. 1,846,301 issued Feb. 23, 1932,1,846,302 issued Feb. 23, 1932, and 1,942,854 issued Jan. 9, 1934;White, U.S. Pat. No. 1,990,507 issued Feb. 12, 1935; Brooker and White,U.S. Pat. Nos. 2,112,140 issued Mar. 22, 1938, 2,165,338 issued July 11,1939, 2,493,747 issued Jan. 10, 1950, and 2,739,964 issued Mar. 27,1956; Brooker and Keyes, U.S. Pat No. 2,493,748 issued Jan. 10, 1950;Sprague, U.S. Pat. Nos. 2,503,776 issued Apr. 11, 1950, and 2,519,001issued Aug. 15, 1950; l-leseltine and Brooker, U.S. Pat. No. 2,666,761issued Jan. 19, 1954; l-leseltine, U.S. Pat. No. 2,734,900 issued Feb.14, 1956; Van Lare, U.S. Pat. No. 2,739,149 issued Mar. 20, 1956;British Pat. No. 450,958 accepted July 15, 1936, and elsewhere in theliterature.

The sensitizing amount of the spectral-sensitizing dyes utili-zed can bewidely varied. The concentration of the dyes will vary according to thetype of emulsion and according to the effect desired. The suitable andmost economical concentration for any given emulsion will be apparent tothose skilled in the art upon making the ordinary tests and observationscustomarily used in the art of emulsion making. Generally about 10 to1000 mg. of dye per mole of silver halide in the emulsion are utilized.About 0.005 to 0.5 mole percent of sensitizing dye based on the silverhalide in the emulsion is a typical working range. A single dye orcombinations of several dyes can be used in the present emulsions forspectral sensitization.

Merocyanine-spectra1-sensitizing dyes are preferably utilized in theemulsions of the invention as stain imparted to emulsions containingsuch dyes is substantially bleached or made colorless duringphotodevelopment. Also, merocyanine dyes tend to be less easilydisplaced or desorbed from the silver-halide crystals of the emulsionsof the invention than cyanine dyes by many halogen acceptors that areutilized in light-developable, direct-print silver-halide emulsions.

Various colloids can be used as vehicles or binding agents in preparingthe silver-halide emulsions of this invention. Satisfactory colloidswhich can be used for this purpose include any of the hydrophiliccolloids generally employed in the photographic field, including, forexample, gelatin, colloidal albumin, polysaccharides, cellulosederivatives, synthetic resins such as polyvinyl compounds, includingpolyvinyl alcohol derivatives, acrylamide polymers and the like. Inaddition to the above hydrophilic colloids, the vehicle or binding agentcan also contain hydrophobic colloids such as dispersed polymerizedvinyl compounds, particularly those which increase the dimensionalstability of photographic materials. Suitable compounds of this typeinclude water-insoluble polymers of alkyl acrylates or methacrylates,acrylic acid, sulfoalkyl acrylates or methacrylates, and the like.

The above-described emulsions of the invention can becoated on a widevariety of supports in accordance with usual practice. Typical supportsfor photographic elements of the invention include glass, metal, paper,polyolefin-coated paper, cellulose nitrate film, cellulose acetate film,polystyrene film, polyester films such as polyethylene terephthalatefilm, heatresistance polymeric films such as high temperature polyester,polyimide, polycarbonate films, and the like.

In one embodiment, a direct-print image can be formed with aphotographic element containing an emulsion of the invention; thephotographic element is initially exposed to a relatively short durationand high-intensity source of electromagnetic radiation (e.g., at leastabout 0.1 foot-candle second at an intensity of more than about 100foot-candles) such as a high-intensity mercury, xenon or X-radiationsource to form a latent image in the emulsion of the photographicelement, and thereafter the resulting latent image is photodeveloped byoverall exposure to a radiation source of lower intensity than theoriginal exposure. Generally, the latent image formed in the emulsion inthe first instance is not visible and does not become visible untilphotodevelopment. Heat can also be utilized during the photodevelopmentstep. Typically, the subject emulsions are heated to a temperature ofabout 90 C. to 200 C. for about 1 to 30 seconds and photodeveloped afterthe initial high-intensity exposure.

Photographic elements containing direct-print emulsions can also belatensified to increase the speed of the emulsion. This can beaccomplished by exposure between the initial high-intensity exposure andphotodevelopment with a filtered light which is filtered to removesubstantially all of the radiation absorbed directly by the silverhalide, but transmits radiation in the regions conferred to the silverhalide by the sensitizing dyes normally used in direct-print emulsions.where the silver halide has been prepared in the presence of a thioetherand/or a lead salt, the latensification procedure is quite useful toimprove speed when the halide of the silver halide is less than about 90percent bromide and the balance is either chloride or iodide. When thesilver halides are prepared in the presence of water-soluble nitrites,similar improvements can be obtained by latensification when thelow-bromide concentrations are utilized.

The invention can be further illustrated by the following examples:

EXAMPLE 1 A direct-print silver chlorobromide emulsion is prepared inthe presence of a thioether and a lead salt as described in example ofMcBride, US. Pat. No. 3,271,157, except 2 grams of NaNO per mole ofsilver is present in the mixture during the formation of thesilver-halide crystals.

To 168 g. of this emulsion containing 0.07 mole of silver melted at 40C. is added a solution containing 2.8 g. urazole and conventionalcoating aids. The emulsion is coated on a single weight paper stock at256 mg. of silver per ft. and 558 mg. of gelatin per ft.

A second emulsion is made and coated in the same way except that the NaNO is omitted.

After drying, one set of coatings is exposed in an Edgerton G and G.Mark IV Sensitometer for 10 seconds modulated by a step tabletcontaining 21 2 steps. The coatings are then photodeveloped by exposingthem to cool white fluorescent lamps at 50 F.C. for 5 minutes. A secondset is incubated one week at 120 F 35 percent RH, exposed andphotodeveloped as above.

Both sets of tests are faded for two weeks by exposure to 50 PC. of coolwhite fluorescent light to give the speeds and densities shown below.

Fresh test incubated test No. of No. of

visibl e visible Emulsion Dmin. AD steps Dmin. AD steps Control 33 25 1432 13 15 +NaNO2 (2 gJAg mole) 31 .28 15 31 .14 16 Similar improvementsare obtained when potassium nitrite, ammonium nitrite and magnesiumnitrite are used in the precipitation in place of the sodium nitrite.

EXAMPLE 2 An emulsion is made and coated as in example 1, except only1.0 g. NaNO /Ag. mole is used and the NaNO and lead salt are dissolvedin water before adding to the gelatin solution.

An emulsion is prepared and coated as in example 1, except that 1.0 g.of NaNO is used and the NaNO lead salt and thioether are dissolved inwater before adding to the gelatin solution.

Fresh test incubated test No. of No. 0

visib l e visibl e Emulsion Dmin AD stops Dmin. AD steps Control 05 153'2 09 i5 +NuNOz (l gJAg mole) 30 .10 16 .31 11 16 it can be seen fromexamples l-3 that the nitrite can be added to the precipitation mediumin a number of ways and it will still provide improvements in thephotographic properties of the resultant emulsion.

EXAMPLE 4 This example demonstrates the effectiveness of thewatersoluble nitrite when used during the precipitation of thesilverhalide grains in contradistinction to the use of the samewatersoluble nitrite when used as a halogen acceptor. Emulsion A isprepared in the presence of a thioether and a lead salt, as described inexample 10, McBride, US. Pat. No. 3,271,157. Emulsion B is prepared inthe presence of a thioether, a lead salt and 1 g. of sodium nitrite persilver mole.

The spectral-sensitizing dye 5-[(5,6-dichloro-l-B-diethylaminoethyl-3-ethyl-2-benzimidazolinylidene)ethylidene1-3- ethyl rhodanine isadded to both emulsions at mg. per silver mole along with otherconventional coating aids. One g. of sodium nitrite per mole of silveris also added to Emulsion A as a coating addendum. The emulsions arethen coated, exposed, processed and incubated for one week as describedin example 1. The following table illustrates the results:

The water-soluble nitrites provide highly improved properties whenincorporated in the grain, as evidenced by Emulsion B as compared withEmulsion A wherein sodium nitrite is added as a halogen acceptor.

EXAMPLE 5 Fresh results Incubation results Addi- N o. of No. of Emulsiontional visible visible number addenda Dmin. AD steps Dmin. AD steps A 28909 28 07 15 II 35 36 16 .33 21 16 I-l-II .34 36 16 34 16 II 34 35 16 3222 17 Improved image properties are also obtained when the halogenacceptors. dithiourazole, dithiourazole hydrazine salt, thiourea,thiosemicarbazide and l-n-butyl-l ,2,5,6-tetrahydro-1,3,5-triazine-4-thiol are used in silver-halide emulsions containinggrains formed in the presence of water-soluble nitrites.

Although the invention has been described in considerable detail withparticular reference to certain preferred embodiments thereof,variations and modifications can be effected within the spirit and scopeof the invention as described hereinbefore and in the appended claims.

I claim:

l. A silver-halide emulsion containing silver-halide grains formed inthe presence of a water-soluble nitrite, said nitrite being present in aconcentration of about 1X10 to about one mole per mole of silver halideformed.

2. A silver-halide emulsion according to claim 1 wherein said grains areformed in the presence of thioether and said water-soluble nitrite.

3. A silver-halide emulsion according to claim 1 wherein said grains areformed in the presence of a water-soluble lead salt, a thioether andsaid water-soluble nitrite.

4. A silver-halide emulsion according to claim 1 wherein said nitrite isan alkali metal nitrite.

5. A silver-halide emulsion according to claim 1 wherein said nitrite issodium nitrite.

6. A direct-print silver-halide composition according to claim 1 whereinsaid silver-halide grains have a predominant amount of radiationsensitivity internal tosaid grains.

7. A silver-halide composition according to claim 1 wherein the halideof said silver halide is predominantly bromide.

8. A direct-print silver-halide composition according to claim 1 furthercomprising a halogen acceptor in admixture with said silver-halidegrains.

9. A direct-print silver-halide composition according to claim 1 furthercomprising a nitrogen-containing halogen acceptor.

10. A direct-print silver-halide composition according to claim 1comprising a urazole compound as a halogen acceptor.

11. A photographic element comprising a support and a layer of thesilver-halide emulsion of claim 1.

12. An improved process for preparing direct-print silverhalideemulsions, the improvement comprising forming the silver-halide grainsof said emulsion in a precipitation medium containing from about 1X10 toabout one mole per mole of silver halide formed of a water-solublenitrite.

mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,615, 580 Dated October 22, 1971 Invent r( Richard Warren Karlson It iscertified that error appears in the above-identified patent: and thatsaid Letters Patent are hereby corrected as shown below:

F- Column 1 line 2L "therein" should read wherein---; 1

line 39, "1x10 should read ---lx1O" Column 3, line35, "where" shouldread ---where--; line 66, "10 should read ---1o""---; line 7, "21 2"should read 2'N'2- line 37, "0" should read -of--- (second oocurenoe)line 2L "909" should read ---.O9---; line 31 sEIould read Claim 1, liu'zg 3, "10 should re 1 "-10" should read ---10 Claim 12, line 1 "1OSigned and sealed this 2nd day of May 1972.

(SEAL) Attest;

EDWARD M.FLETCHER,Jz-. ROBERT GOT'ISCHALK Attesting Officer Commissionerof Patents

2. A silver-halide emulsion according to claim 1 wherein said grains areformed in the presence of thioether and said water-soluble nitrite.
 3. Asilver-halide emulsion according to claim 1 wherein said grains areformed in the presence of a water-soluble lead salt, a thioether andsaid water-soluble nitrite.
 4. A silver-halide emulsion according toclaim 1 wherein said nitrite is an alkali metal nitrite.
 5. Asilver-halide emulsion according to claim 1 wherein said nitrite issodium nitrite.
 6. A direct-print silver-halide composition according toclaim 1 wherein said silver-halide grains have a predominant amount ofradiation sensitivity internal to said grains.
 7. A silver-halidecomposition according to claim 1 wherein the halide of said silverhalide is predominantly bromide.
 8. A direct-print silver-halidecomposition according to claim 1 further comprising a halogen acceptorin admixture with said silver-halide grains.
 9. A direct-printsilver-halide composition according to claim 1 further comprising anitrogen-containing halogen acceptor.
 10. A direct-print silver-halidecomposition according to claim 1 comprising a urazole compound as ahalogen acceptor.
 11. A photographic element comprising a support and alayer of the silver-halide emulsion of claim
 1. 12. An improved processfor preparing direct-print silver-halide emulsions, the improvementcomprising forming the silver-halide grains of said emulsion in aprecipitation medium containing from about 1 X 10 5 to about one moleper mole of silver halide formed of a water-soluble nitrite.